This invention relates generally to sensing methods and apparatus and more particularly to sensing methods and apparatus for monitoring abrasive waterjet machining of engineering materials.
Abrasive water jet (AWJ) processes employ abrasive materials entrained into a high-pressure waterjet to perform a variety of cutting and other machining operations on a variety of materials. The high-energy waterjet beam utilized combines a rapid erosion of a workpiece material by high speed solid particle impacts with rapid cooling provided by a waterjet. In AWJ cutting operations an abrasive waterjet pierces through the thickness of and is then moved along a material to be cut.
In performing machining operations such as AWJ cutting, various physical dimensions such as workpiece thickness must be measured in order to properly configure the water pressure, abrasive flow rate, and other system parameters for the AWJ apparatus. Additionally, the proximity of and distances between various components of the AWJ apparatus and the workpiece must be monitored. For example, the proximity of an AWJ nozzle to a workpiece must be monitored with respect to establishing and maintaining air gap and stand-off distances within acceptable tolerance ranges. Additionally physical events such as the moment of pierce-through of a workpiece by an AWJ waterjet during a cutting operation must also be detected in order to establish when the relative motion between the workpiece and an AWJ nozzle should be commenced.
Although the measuring and monitoring of these and other physical aspects may be done by visual inspection and manual control by an operator, this is generally a cumbersome and not very precise method for controlling such machining operations. The foregoing illustrates limitations known to exist in present machining methods and apparatus. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly a suitable alternative is provided by the multi-functional sensing methods and apparatus of the present invention, which include features more fully disclosed herein.